May is the climax of the Maine spring — the warbler migration crests, the woods fill with trillium and lady's slipper buds, lilacs bloom, and the gardens finally release from frost. It is the most exhilarating month of the natural year, and Monhegan Island becomes a magnet for migrant songbirds and birders alike.
Week by week in May
April 30 – May 6
- The warbler migration begins to build, and Monhegan Island starts drawing exhausted migrant songbirds and the birders who chase them.
- Fiddleheads — the tight coiled croziers of the ostrich fern, a beloved Maine specialty — appear for just a couple of weeks alongside the first asparagus. Cook them thoroughly before eating — boil 15 minutes or steam 10–12; never raw.
- Serviceberry blooms white along woodland edges, the first of the flowering trees, followed soon by wild cherry and chokecherry.
May 7–13
- Warbler migration crests — yellow, magnolia, chestnut-sided, and blackburnian pour through, and Monhegan Island is at its famous spring peak.
- Trailing arbutus (mayflower) scents sandy pine woods, and the first pink lady's slipper buds rise under pine and oak.
- Harden off warm-season seedlings over a week of increasing outdoor exposure, and keep sowing cool-season crops while frost danger lingers.
May 14–20
- Atlantic puffins, razorbills, and terns are back on Eastern Egg Rock and Machias Seal Island — the birds return in late April — and the seabird boat tours begin.
- Lilacs reach their fragrant peak in dooryards statewide, and apple and crabapple blossom fills the orchards pink and white.
- The first northbound monarchs reach Maine, the females laying eggs on emerging milkweed to start the summer's home-grown broods.
May 21–27
- On the warm coast the frost date passes — set out tomatoes, peppers, and squash, and direct-sow beans and corn into the warming soil.
- Magenta rhodora lights up the bogs and barrens, and the first lupines begin along the Midcoast roadsides.
- The dawn chorus is at its fullest — rose-breasted grosbeaks, scarlet tanagers, and Baltimore orioles sing on territory across the state.
May 28 – June 3
- Lupines build toward their famous June peak, washing roadsides and coastal headlands across the Midcoast in spires of blue and purple.
- In the cold interior and north, the last frost finally passes and warm-season crops can go out — keep row cover ready for late cold snaps.
- Canadian tiger swallowtails, large and yellow, float along forest edges and dirt roads, the season's first big showy butterfly.
Birds This Month
May is the single best birding month in Maine, and the headline is the warbler migration. Wave after wave of tiny brilliant songbirds pours north — yellow, magnolia, chestnut-sided, black-throated green, blackburnian, Canada, Cape May, and dozens more — peaking in the second and third weeks. The legendary spot is Monhegan Island, a migrant trap where exhausted songbirds drop in by the hundreds, but every wooded park and yard fills with birds. With them come Baltimore orioles, rose-breasted grosbeaks, scarlet tanagers, indigo buntings, ruby-throated hummingbirds, and a flood of flycatchers, vireos, and thrushes.
On the water, common loons settle onto nesting lakes, and the seabird colonies fire up: Atlantic puffins, razorbills, and terns — back since late April — settle in at Eastern Egg Rock and Machias Seal Island, and the boat tours begin. North Woods specialties — boreal chickadee, spruce grouse, and breeding warblers — are singing on territory. Hang oriole and hummingbird feeders by the first week, and listen at dawn for the fullest chorus of the year.
What's Blooming
May is the peak of Maine's spring wildflowers. The hardwood-forest ephemerals reach their climax early in the month — red trillium and painted trillium, wild oats, Canada mayflower, starflower, wild columbine, and foamflower carpet the woods, alongside the lingering trout lily and bloodroot. The tiny pink-and-white trailing arbutus (mayflower), Maine's beloved early-spring wildflower and a low evergreen member of the heath family, scents sandy pine woods.
By late May the magenta rhodora lights up the bogs and barrens — the wild azalea Emerson made famous — and the first lupines begin along Midcoast roadsides. Lilacs reach their fragrant peak in dooryards statewide, and apple and crabapple blossom fills the orchards. In the gardens, tulips, daffodils, and the first bearded iris bloom. The forest-floor ephemerals fade fast as the canopy closes, so the first half of May is the window to see them.
Garden This Month
May is Maine's big planting month, but it pivots on the last-frost date — mid-to-late May on the warm coast, late May to early June in the cold interior and north. Early in the month, keep sowing and harvesting cool-season crops: peas, lettuce, spinach, radishes, carrots, beets, potatoes, onions, and brassicas all thrive. Harden off your warm-season seedlings over a week of increasing outdoor exposure so they don't shock when transplanted.
Once the frost date passes for your area, set out tomatoes, peppers, eggplant, squash, cucumbers, and basil, and direct-sow beans, corn, and melons into warm soil. Watch the forecast vigilantly — a late frost can still strike, especially inland, so keep row cover or old sheets ready. In the flower garden, plant annuals after frost, divide perennials, and mulch beds to hold moisture for the short, dry-spelled summer ahead.
Zone 3b (Aroostook & far north): the last frost can come into early June here. Direct-sow hardy greens, peas, and roots now, but keep tomatoes, peppers, and squash indoors or under cover until very late May or early June.
Zone 4b (interior & mountains): the last frost is typically late May. Harden off warm-season transplants and set them out only after the frost date passes near month's end, keeping row cover ready for late cold snaps.
Zone 5b (Midcoast & south): the warmest gardens reach their last frost around the third week. After about May 20–25, set out tomatoes, peppers, and cucurbits and direct-sow beans and corn, watching for any late frost.
What's at the Farmers Market
May reopens Maine's outdoor farmers markets in force and brings the first true spring harvest. Fiddleheads — the tight coiled croziers of the ostrich fern, a beloved Maine specialty — appear for just a couple of weeks early in the month, alongside asparagus, rhubarb, and a flush of greenhouse and early-field spinach, lettuce, arugula, radishes, and green onions. Late May may bring the first overwintered spinach and hoop-house crops.
This is the biggest plant-sale season of the year, with markets and nurseries overflowing with vegetable seedlings, herbs, hanging baskets, and native perennials for gardeners racing to plant after the frost date. Choose fiddleheads that are tightly coiled and firm and refrigerate them dry in a paper bag, using within a day or two — and always cook them thoroughly (boil 15 minutes or steam 10–12; never raw); pick asparagus with tight tips and stand it upright in a little water. The markets are at their most energetic of the early season.
Night Sky This Month
May's mild nights make for relaxed stargazing in Maine, though the nights are shortening fast toward the solstice. The spring sky is at its best: the Big Dipper rides high overhead, brilliant orange Arcturus in Boötes commands the eastern sky, and blue-white Spica in Virgo and the keystone of Hercules climb behind it. Late at night the first of the Summer Triangle stars, Vega, clears the eastern horizon.
The Eta Aquariid meteor shower — debris from Halley's Comet — peaks in early May, though its low radiant makes it a modest show from Maine's latitude, best in the pre-dawn hours. Late-spring nights remain good for the northern lights from the dark north country when geomagnetic activity spikes. Acadia's relatively dark coastal skies and the deep interior both reward a late-evening look. As always, the printable Maine night-sky guide lists this year's meteor-peak dates, planet positions, and aurora outlook for your region.
Butterflies & Pollinators
May is when Maine's butterfly season truly opens. The big arrival is the monarch — the first northbound generation reaches the state late in the month, the females laying eggs on emerging milkweed to start the summer's home-grown broods. The year's first Canadian tiger swallowtails, large and yellow, float along forest edges and dirt roads, and small spring azures, cabbage whites, and clouded sulphurs are common in open ground.
The overwintered mourning cloaks and commas are still around, looking worn now, and migrant red admirals and painted ladies may arrive, sometimes in numbers. Watch lilacs, dandelions, and the first wild blooms for nectaring butterflies on warm, sunny afternoons. To support them, get native milkweed and a succession of nectar plants established now — the monarchs laying eggs this month launch the generations that will eventually make the great fall migration down the Maine coast.
Trees This Month
May is full leaf-out across most of Maine, the woods transforming from bare gray to soft green within a few weeks (later in the far north). The flowering trees take center stage: serviceberry (shadbush) blooms white first along woodland edges, followed by wild cherry, chokecherry, hawthorn, and the orchard apples and crabapples in pink and white. Striped maple and mountain maple hang their delicate flower chains in the understory.
The conifers push their new growth — white and red pines send up pale 'candles,' the balsam firs and spruces flush bright with soft new needles, and the tamaracks are fully feathered green in the bogs. Oaks, beech, and ash are the last to leaf out, finally unfurling as the frost danger passes, and oak pollen dusts the air. By late May the canopy has closed over the forest floor, ending the brief sunlit window the spring ephemerals depended on.
Weather & Daylight
Across Maine, a typical May day averages a high near 63°F and a low near 40°F, with about 3.7 inches of precipitation — statewide averages from the 1991–2020 U.S. climate normals.
Mild and green, comfortable 60s by day cooling into crisp 40-degree nights, with frequent showers feeding new growth.
| Average high | 63°F |
|---|---|
| Average low | 40°F |
| Precipitation | 3.7 in |
| Sunrise (mid-month) | 5:10 ET |
| Sunset (mid-month) | 19:57 ET |
Figures are statewide averages over the 1991–2020 U.S. climate normals; local conditions vary with elevation and distance from the coast. Sunrise and sunset are computed for a midstate point on the 15th (ET).
Next month's version of this page, by email
One short note when Maine's next month turns — what's arriving, blooming, and worth a night outside.
Go deeper with the Maine guides
The complete Maine birding, native-plant, and night-sky references — or the whole year, week by week, in one book.
Same month elsewhere: May in Maryland · May in Massachusetts · May in Michigan